The present invention concerns a brake unit, in particular for use in utility vehicles.
Brake units are already known in the prior art in which an expansion wedge unit is used to move two brake shoes or brake linings relative to each other such that they come into engagement with the brake disc or a brake drum. In particular, the force-transmitting parts of the expansion wedge unit are exposed to high mechanical loads, wherein due to the relative movements taking place under slip friction between the various components, often a high wear occurs and also a high force is required for the actuating unit. It has proved useful to insert roller bodies between the parts of the expansion wedge unit which move relative to each other, such that instead of a sliding movement of the components, a rolling movement is possible and hence the wear on the force-transmitting faces is reduced. The solutions known from the prior art however have revealed the problem that very high surface pressures occur on the individual roller bodies, and hence surface damage results at the force-transmitting faces of the components which move relative to each other. It has furthermore proved problematical that, on a pivoting of the expansion wedge relative to the piston elements which apply force to the brake shoes in operation of the brake, high stress peaks occur which again cause increased material wear and a shorter service life of the expansion wedge units known from the prior art.
The object of the present invention is to provide a brake unit which eliminates the disadvantages known from the prior art and nonetheless allows simple and compact construction.